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1.
(n) - A concise, clever statement you don't think of until it's too late
"D*mn why do I think of good comebacks after arguements. Stupid Afterism."
by Xx T N T xX June 28, 2004
 
2.
Thinking of a witty statement, comeback, or argument, but only after the opportunity has passed and the conversation has moved on to a new subject.
1. "Ya well at least 'I' wasn't in remedial math!"

"What?"

"Y'know, about what you said earlier..."

"Man you've got some serious afterism goin on."

2. "Hey remember that cow we saw on the road back there? Well it looked like Jessic-"

"That was like half an hour ago?"

"Ya but... nevermind."
by Dwilkins June 12, 2009